We formed C(sp3)–C(sp2) bonds under electrochemical conditions by using NHP esters and N-heteroarenes without any catalysts. Our approach could be a complement to the Kolbe reaction and a promising strategy for finding more new reactions.
Electrocatalytic CO 2 reduction to value-added chemicals is a promising route to address the global warming problem. However, it still confronts low conversion efficiency and poor selectivity, due to difficulties in activating the inert CO 2 molecule and controlling the complex reaction pathways. Here, we put forward an unconventional approach to activating CO 2 by utilizing the quasi-reversible bonding between electrochemically reduced quinone groups and CO 2 . Through surface modification with polyquinone, the C 2+ production is effectively enhanced on a polycrystalline Cu foil model electrode. By further incorporating the polyquinone into a Cu gas diffusion electrode (GDE), a high C 2 H 4 partial current density of 325 mA/cm 2 is achieved at a low cell voltage of 3.5 V for CO 2 /pure water coelectrolysis. Combined with in situ ATR-SEIRAS study, the increased C 2+ product selectivity is attributed to the quinone-accelerated CO 2 -to-*CO conversion, which creates a high *CO coverage on Cu surface and thus facilitates C−C coupling for C 2+ production.
Two kinds of biodegradable polymers, poly(e-caprolactone) (PCL) and poly[(alanino ethyl ester) 0.67 (glycino ethyl ester) 0.33 phosphazene] (PAGP), were electrospun by using four different solvents. All PCL nanofibrous mats had similar surface water contact angles independent of solvents. However, it was found that the water contact angles of PAGP nanofibrous mats were 102.2 AE 2.3 , 113.5 AE 2.2 , 115.8 AE 1.4 , and 119.1 AE 0.7 , respectively, when trifluoroethanol, chloroform, dichloromethane, and tetrahydrofuran were used as a solvent. This difference was supposed mainly due to phosphorous and nitrous atoms in PAGP being dragged to fiber surface with solvent evaporation during the solidification of nanofibers, because of the strong interaction between positive phosphorous atoms and electronegative atoms in solvents. This interaction was confirmed by Fourier Transform Infrared, and the accumulation of phosphorous and nitrous atoms in the solvent-casting PAGP film surface was identified by X-ray photoelectron spectrometry analysis. PCL samples did not show the solvent-controlled surface wettability because it contained fewer polar atoms.
Polyacrylonitrile (PAN) fibers were pre-oxidized in a temperature range of 180-275°C. The effects of positive and negative stretching on the structure and morphology of PAN fiber in the pre-oxidation process were studied by FTIR spectroscopy, XRD, and SEM. Mechanical property changes were also investigated. No changes in the movement and intensity of functional groups of PAN fibers were caused by positive stretching of up to 10% and negative stretching down to-8%. The crystal structure can be affected by the positive stretching and negative stretching. The maximum strength is 479.81 MPa when the stretching is positive, and the maximum strength is 420.55 MPa when the stretching is negative.
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